Describe the bug
Replace these lines with your description. Be as specific as possible and list steps to reproduce the issue. If you have any suggestions for the solution please list that as well.

If you have installed pyRevit, and the installation completed with no errors but pyRevit doesn't load, please run the command below in terminal. This should fix the issue on your machine, however, please continue filing the issue with instructions below.

pyrevit attach master 277 --installed

To Reproduce
Steps to reproduce the behavior:

1. Go to PyRevit-PreFilght Checks
2. Click on PyRevit-PreFilght Checks

Desktop (please complete the following information):

• OS: [e.g. Winid 10]
• pyRevit Version [v4.8.8]
• pyRevit Environment: Open a command prompt and run the command below. Replace these lines with the results. Take a look at this markdown guide and wrap the command results in ``` when pasting here for correct formatting.

pyrevit env

Microsoft Windows [Version 10.0.19041.1052]
(c) Microsoft Corporation. All rights reserved.

C:\Users\rob.cross>pyrevit env
==> Registered Clones (full git repos)
==> Registered Clones (deployed from archive/image)
master | Deploy: "basepublic" | Branch: "master" | Version: "4.8.8" | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
==> Attachments
master | Product: "Autodesk Revit 2022" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
master | Product: "Autodesk Revit 2021" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
master | Product: "Autodesk Revit 2020" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
master | Product: "Autodesk Revit 2019" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
master | Product: "2018.3.3 Security Fix" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
master | Product: "2017.2.5 Security Fix" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
master | Product: "2016.1.9 Security Fix" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
master | Product: "2015 Release 2 (Subscription only release)" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
master | Product: "2014 Update Release 3" | Engine: IPY277 (277) | Path: "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master"
==> Installed Extensions
==> Default Extension Search Path
C:\Users\rob.cross\AppData\Roaming\pyRevit\Extensions
==> Extension Search Paths
==> Extension Sources - Default
https://github.com/eirannejad/pyRevit/raw/master/extensions/extensions.json
==> Extension Sources - Additional
==> Installed Revits
Autodesk Revit 2022 | Version: 22.0.10.28 | Build: 20210616_0115(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2022"
Autodesk Revit 2021 | Version: 21.1.30.74 | Build: 20210426_1515(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2021"
Autodesk Revit 2020 | Version: 20.2.40.65 | Build: 20210420_1515(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2020"
Autodesk Revit 2019 | Version: 19.2.30.41 | Build: 20210416_1515(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2019"
2018.3.3 Security Fix | Version: 18.3.3.18 | Build: 20190510_1515(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2018"
2017.2.5 Security Fix | Version: 17.0.1169.0 | Build: 20190508_0315(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2017"
2016.1.9 Security Fix | Version: 16.0.1218.0 | Build: 20190508_0715(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2016"
2015 Release 2 (Subscription only release) | Version: 15.0.1103.0 | Build: 20140905_0730(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2015"
2014 Update Release 3 | Version: 13.11.4 | Build: 20140709_2115(x64) | Language: 1033 | Path: "C:\Program Files\Autodesk\Revit 2014"
==> Running Revit Instances
Error: Object reference not set to an instance of an object.
Run with "--debug" option to see debug messages

C:\Users\rob.cross>

Additional context
IronPython Traceback:
Traceback (most recent call last):
File "C:\Users\rob.cross\AppData\Roaming\pyRevit\Extensions\pyRevitTools.extension\pyRevit.tab\Project.panel\Preflight Checks.pushbutton\script.py", line 32, in
File "C:\Users\rob.cross\AppData\Roaming\pyRevit\Extensions\pyRevitTools.extension\pyRevit.tab\Project.panel\Preflight Checks.pushbutton\script.py", line 16, in ask_for_preflight_checks
File "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master\pyrevitlib\pyrevit\preflight_init_.py", line 81, in get_all_preflight_checks
File "C:\Users\rob.cross\AppData\Roaming\pyRevit-Master\extensions\pyRevitTools.extension\checks\modelchecker_Warnings_check.py", line 16, in
IOError: System.IO.IOException: Could not add reference to assembly RevitServices
at IronPython.Runtime.ClrModule.AddReference(CodeContext context, String name)
at IronPython.Runtime.ClrModule.AddReference(CodeContext context, Object[] references)
at Microsoft.Scripting.Interpreter.ActionCallInstruction2.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.LightLambda.Run4[T0,T1,T2,T3,TRet](T0 arg0, T1 arg1, T2 arg2, T3 arg3) at IronPython.Compiler.Ast.CallExpression.Invoke1Instruction.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.LightLambda.Run1[T0,TRet](T0 arg0) at IronPython.Compiler.RuntimeScriptCode.InvokeTarget(Scope scope) at IronPython.Runtime.PythonContext.InitializeModule(String fileName, ModuleContext moduleContext, ScriptCode scriptCode, ModuleOptions options) at IronPython.Modules.PythonImport.load_source(CodeContext context, String name, String pathname) at Microsoft.Scripting.Interpreter.FuncCallInstruction4.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.LightLambda.Run5[T0,T1,T2,T3,T4,TRet](T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4)
at System.Dynamic.UpdateDelegates.UpdateAndExecute4[T0,T1,T2,T3,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2, T3 arg3)
at IronPython.Compiler.Ast.CallExpression.Invoke2Instruction.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.LightLambda.Run1[T0,TRet](T0 arg0)
at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1)
at Microsoft.Scripting.Interpreter.DynamicInstruction3.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.LightLambda.Run1[T0,TRet](T0 arg0) at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1) at Microsoft.Scripting.Interpreter.DynamicInstruction3.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.LightLambda.Run2[T0,T1,TRet](T0 arg0, T1 arg1)
at IronPython.Compiler.PythonScriptCode.RunWorker(CodeContext ctx)
at PyRevitLabs.PyRevit.Runtime.IronPythonEngine.Execute(ScriptRuntime& runtime)

Script Executor Traceback:
System.IO.IOException: Could not add reference to assembly RevitServices
at IronPython.Runtime.ClrModule.AddReference(CodeContext context, String name)
at IronPython.Runtime.ClrModule.AddReference(CodeContext context, Object[] references)
at Microsoft.Scripting.Interpreter.ActionCallInstruction2.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.LightLambda.Run4[T0,T1,T2,T3,TRet](T0 arg0, T1 arg1, T2 arg2, T3 arg3) at IronPython.Compiler.Ast.CallExpression.Invoke1Instruction.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.LightLambda.Run1[T0,TRet](T0 arg0) at IronPython.Compiler.RuntimeScriptCode.InvokeTarget(Scope scope) at IronPython.Runtime.PythonContext.InitializeModule(String fileName, ModuleContext moduleContext, ScriptCode scriptCode, ModuleOptions options) at IronPython.Modules.PythonImport.load_source(CodeContext context, String name, String pathname) at Microsoft.Scripting.Interpreter.FuncCallInstruction4.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.LightLambda.Run5[T0,T1,T2,T3,T4,TRet](T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4)
at System.Dynamic.UpdateDelegates.UpdateAndExecute4[T0,T1,T2,T3,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2, T3 arg3)
at IronPython.Compiler.Ast.CallExpression.Invoke2Instruction.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.LightLambda.Run1[T0,TRet](T0 arg0)
at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1)
at Microsoft.Scripting.Interpreter.DynamicInstruction3.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame) at Microsoft.Scripting.Interpreter.LightLambda.Run1[T0,TRet](T0 arg0) at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1) at Microsoft.Scripting.Interpreter.DynamicInstruction3.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.Interpreter.Run(InterpretedFrame frame)
at Microsoft.Scripting.Interpreter.LightLambda.Run2[T0,T1,TRet](T0 arg0, T1 arg1)
at IronPython.Compiler.PythonScriptCode.RunWorker(CodeContext ctx)
at PyRevitLabs.PyRevit.Runtime.IronPythonEngine.Execute(ScriptRuntime& runtime)